1. Field of the Invention
The invention is generally related to the area of optical communications. In particular, the invention is related to pluggable optical passive devices.
2. The Background of Related Art
To meet the ever-increasing demands for high bandwidth and more flexibility in modern communication networks, utilizing optical fiber networks capable of transmitting multiplexed channel signals is becoming increasingly popular. Many optical devices have been designed to meet the demands. Among the optical devices, pluggable optical units are key elements in many applications of optical fiber communications. A cost-effective and reliable optical pluggable unit having low insertion loss and versatile function with flexibility is often required. FIG. 1 duplicates FIG. 1 of U.S. Pat. No. D467,544 to show a small form-factor pluggable optical transceiver module.
Optical add/drop devices are those elements often used in optical systems and networks. For example, an exchanging of data signals involves the exchanging of matching wavelengths from two different sources within an optical network. In other words, the multi-channel signal would drop a wavelength while simultaneously adding a channel with a matching wavelength at the same network node. FIG. 2 duplicates FIG. 2 of US Pat. Pub. No.: 2006/0018593 A1 to show the concept of add/drop function in the optical add/drop devices.
Typically the add/drop function is realized with bulky LGX or rack modules and rarely in small form factor, although there are some configurations with multiple SFP form factor devices. One example is shown in FIG. 3 that duplicates FIG. 3 of US Pat. Pub. No.: 2009/0154930 A1.
Pluggable devices are widely available in electronic forms these days. A device that belongs to the pluggable category typically needs to be turned on and functioning as soon as it is inserted into an electrical connector receptacle or adaptor port. When it is unplugged from such a receptacle, neither the system that hosts the pluggable device nor the pluggable device itself will be damaged. Pluggable devices may be added or removed from a system without interrupting the synchronization between the devices and the system. Therefore, it is not required to have a power reset when replacing or upgrading such devices. Pluggable devices add on a good deal of system application upgrade flexibilities and are becoming more and more popular for electronics.
The advances in opto-electronics also allow people to expand communication transmitters and receivers or the so-called transceivers and transponders into the pluggable domain. Various formats for such devices are being proposed: Small Form Pluggable (SFP) is an example. Other examples that allow pluggable applications include XFP, I2C, RS-232, USB, Dual-port RAM, and Ethernet.
This invention disclosure intends to introduce a stand-alone small form factor device to fulfill the functionality of adding or dropping a channel signal and to be added into the pluggable application categories.